Upper Provided With Sponge Member in Heel Part

ABSTRACT

An upper includes an inner skin placed on a wear&#39;s skin side, and an outer skin placed on an opposite side from the inner skin, wherein a sponge member is housed between the inner skin and the outer skin in a heel portion; the sponge member includes a medial side portion covering a medial side of a calcaneal bone, and a lateral side portion covering a lateral side of the calcaneal bone; and in a developed view where the sponge member is unfolded into a planar shape, a height of a lateral first centroid of a portion corresponding to the lateral side portion is set to be higher than a height of a medial first centroid of a portion corresponding to the medial side portion.

TECHNICAL FIELD

The present invention relates to an upper having a sponge member in a heel portion.

BACKGROUND ART

Shoes having a sponge member in the heel portion in order to improve the fit of the heel portion of the upper are well known in the art.

CITATION LIST Patent Literature

First Patent Document: JP2011-041590 A (abstract)

Second Patent Document: JP2010-022791 A (abstract)

SUMMARY OF INVENTION

There have been no researches in the prior art on the sponge member conducted while sufficiently taking into consideration the change in the shape of the foot. Therefore, in the prior art, the conformity of the upper to the foot (the fitting property) has not been satisfactory.

It is therefore an object of the present invention to provide an upper having a sponge member in a heel portion, with which it is possible to improve the fitting property of the upper.

Principle of the Invention

Prior to the description of the configuration of the present invention, the principle of the present invention will be presented through experiments and discussions done by the present inventors.

Referring to FIGS. 1A and 1B, a large number of markers M were attached to the foot of the subject in a five-by-five matrix pattern. FIGS. 1C and 1D show images of the markers M in a standstill position. Note that the markers M are connected with one another by vertical lines and horizontal lines so as to make the images easier to view.

Then, the subject ran as shown in FIGS. 2( a) to 2(e), and images of the markers M were captured at different phases, including heel contact HC of FIG. 2( a), foot flat FF of FIG. 2( b), mid stance MS of FIG. 2( c), heel rise HR of FIG. 2( d), and toe off TO of FIG. 2( e).

FIGS. 2( f) to 2(j) show images on the back side, and FIGS. 2( k) to 2(o) show images on the lateral side. In these figures, M1 denotes a marker attached to the medial ankle, whereas M2 denotes a marker attached to the lateral ankle.

First, looking at FIGS. 2( f) to 2(j) while focusing on the medial side Med of the foot, one will notice that the portion below the marker M1 of the medial ankle is narrowed increasingly toward the bottom throughout the entire motion period, and will notice that the narrowing particularly increases during toe off TO. Therefore, it is expected that for the medial side Med of the foot, the slippage off the upper will decrease by inserting a thick sponge in a lower portion Fu.

On the other hand, looking at FIGS. 2( f) to 2(j) while focusing on the lateral side Lat of the foot, one will notice that the portion below the marker M2 of the lateral ankle is such that an area Fa immediately below the lateral ankle is narrowed throughout the entire motion period, and that the narrowing decreases during toe off TO. Therefore, it is expected that for the lateral side Lat of the foot, the slippage off the upper will decrease by inserting a thick sponge in an upper portion of the foot immediately below the lateral ankle.

Looking at FIGS. 2( k) to 2(o) while focusing on the back side of the foot, one will notice that the portion posterior to the lateral ankle, i.e., the area of the Achilles tendon, is narrowed increasingly toward the top over the period of heel contact HC to heel rise HR, but the narrowing decreases dramatically at the moment of toe off TO. On the other hand, one will notice that the area Fb at generally the same level as on the lateral side of the foot is narrowed throughout the entire period. It is assumed that this area Fb is behind the calcaneal tuberosity Cp. The lower end portion of the Achilles tendon is attached to the calcaneal tuberosity Cp, and a portion of the Achilles tendon that is above the calcaneal tuberosity Cp is substantially displaced during motion whereas the calcaneal tuberosity Cp itself does not substantially change during motion. Therefore, it is expected that for the back side, the slippage off the upper will decrease by inserting a thick sponge in the area of the calcaneal tuberosity Cp at generally the same level as on the lateral side Lat of the foot.

Then, the present inventors verified the hypothesis by the following method.

First, three different prototypes were provided, which had the same shoe structure with their arrangements of the sponge plate being different from one another. That is, there were provided Type 1 shown in FIGS. 3( a) to 3(c), Type 2 shown in FIGS. 3( d) to 3(f), and Type 3 shown in FIGS. 3( g) to 3(i). These types of shoes are basically of the same structure, only with their arrangements of the sponge plate Sp indicated by broken lines being different from one another. Note that reference numeral 1 denotes an upper, and reference numeral 2 a sole.

Next, while the subject ran, the amount of vertical slippage between the shoe and the foot over the tread period was measured, obtaining a measurement result indicating that Type 2 had a smaller amount of vertical slippage than Type 1 and Type 3. It is believed that this result agrees with the hypothesis, and that the hypothesis is probably right.

As the thickness of the sponge plate Sp was varied from 5 mm to 10 mm to 15 mm with Type 2, the amount of slippage was particularly small when a 10 mm or 15 mm sponge plate Sp was installed.

An upper 1 of the present invention includes an inner skin 11 placed on a wear's skin side (a side to face a wear's skin), and an outer skin 12 placed on an opposite side from the inner skin 11, wherein a sponge member 3 is housed between the inner skin 11 and the outer skin 12 in the heel portion 10;

the sponge member 3 includes a medial side portion 34 covering a medial side of a calcaneal bone Ca, and a lateral side portion covering a lateral side of the calcaneal bone Ca; and in a developed view where the sponge member 3 is unfolded into a planar shape (plane figure), a level of a lateral first centroid O10 of a portion corresponding to the lateral side portion is set to be higher than a level of a medial first centroid O11 of a portion corresponding to the medial side portion 34.

In this case, the level of the lateral first centroid O10 is higher than the level of the medial first centroid O11. Therefore, the sponge member 3 is placed in an area where the shape of the foot is hollowed and does not change substantially, i.e., in the lower portion directly below the medial ankle of the foot and in an area immediately below the lateral ankle of the foot, and the fit will therefore improve.

In the present invention, a sponge member refers to a member of a foamed synthetic resin or a foamed rubber that easily deforms under a load of an external force and that generally restores its original shape upon removal of the external force. A sponge member may be a member that is cut off or cut out from a sponge plate of a predetermined thickness, or may be obtained by subjecting such a member to secondary molding in a mold. Moreover, a sponge member may be a member individually foamed and molded in a mold.

Note that in the present invention, the centroid means the center of a shape.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are a slant back side view and a slant lateral side view, respectively, showing a foot with markers attached thereto, and FIGS. 1C and 1D are a back side view and a lateral side view, respectively, showing captured positions of the markers in a standstill position.

FIG. 2 shows a test method and a test result, wherein (a) to (e) are schematic side views showing the running form from heel contact to toe off, (f) to (j) are images capturing the markers from the back side from heel contact to toe off, and (k) to (o) are images capturing the markers from the lateral side over the same period.

FIG. 3 shows arrangements of the sponge plate in test samples, wherein (a), (b) and (c) are a medial side view, a back side view and a lateral side view, respectively, of the heel portion of a shoe of Type 1, (d), (e) and (f) are a medial side view, a back side view and a lateral side view, respectively, of the heel portion of a shoe of Type 2, and (g), (h) and (i) are a medial side view, a back side view and a lateral side view, respectively, of the heel portion of a shoe of Type 3.

FIG. 4 is a conceptual lateral cross-sectional view of an upper according to Embodiment 1 of the present invention.

FIGS. 5A to 5D relate to Embodiment 1, wherein FIG. 5A is a plan view of a sponge member, FIG. 5B is a cross-sectional view thereof, FIG. 5C is a medial side view showing the relationship between the sponge member and the foot, and FIG. 5D is a lateral side view showing the same.

FIGS. 6A to 6D relate to Embodiment 2, wherein FIG. 6A is a plan view of a sponge member, FIG. 6B is a cross-sectional view thereof, FIG. 6C is a medial side view showing the relationship between the sponge member and the foot, and FIG. 6D is a lateral side view showing the same.

FIGS. 7A to 7D relate to Embodiment 3, wherein FIG. 7A is a plan view of a sponge member, FIG. 7B is a cross-sectional view thereof, FIG. 7C is a medial side view showing the relationship between the sponge member and the foot, and FIG. 7D is a lateral side view showing the same.

FIGS. 8A to 8D relate to Embodiment 4, wherein FIG. 8A is a plan view of a sponge member, FIG. 8B is a cross-sectional view thereof, FIG. 8C is a medial side view showing the relationship between the sponge member and the foot, and FIG. 8D is a lateral side view showing the same.

DESCRIPTION OF EMBODIMENTS

Preferably, the medial side portion 34 covers at least a portion of a lower edge Ce of the calcaneal bone Ca directly below a talus Ta, and the lateral side portion 35 covers an area of the calcaneal bone Ca directly above a point O, wherein the point O bisects a distance between a lowermost end point Ae of a lateral ankle A0 and the lower edge Ce of the calcaneal bone Ca.

In this case, the medial side portion 34 of the sponge member 3 fills the narrowed portion directly below the talus Ta. On the other hand, the lateral side portion 35 of the sponge member 3 fills the narrowed portion directly and immediately below the lateral ankle A0. Therefore, narrowed portions on the medial side and the lateral side of the heel will be filled, and the upper 1 will better fit the heel.

More preferably, the sponge member 3 includes a thin portion 3 a having a small thickness, and a thick portion 3 b thicker than the thin portion 3 a, and wherein with the sponge member 3 unfolded, a perimeter of the thick portion 3 b is surrounded by the thin portion 3 a.

In this case, the thick portion 3 b protrudes with respect to the thin portion 3 a, and the triangular narrowed portions on the medial side and the lateral side of the heel will likely be filled by the protruding area.

More preferably, in a developed view where the thick portion 3 b is unfolded into a planar shape,

a level of a lateral second centroid O20 of a portion of the thick portion 3 b corresponding to the lateral side portion is set to be higher than a level of a medial second centroid O21 of a portion of the thick portion 3 b corresponding to the medial side portion 34.

The level of the lateral second centroid O20 of the thick portion 3 b is higher than the medial second centroid O21 of the thick portion 3 b. Therefore, the thick portion 3 b is placed in an area where the shape of the foot is hollowed or narrowed and does not change substantially, i.e., in the lower portion directly below the medial ankle of the foot and in an area directly (nearly immediately) below the lateral ankle of the foot, and the fitting property will therefore further improve.

Preferably, a lower edge line 3 bL of the thick portion 3 b extends, while being upwardly slanted, from a medial side of the heel portion 10 to a lateral side thereof via a back side thereof.

In this case, the thick portion 3 b will likely fill the gap in the lower portion of the heel portion 10 on the medial side of the heel portion 10, fill the gap behind the calcaneal tuberosity Cp on the back side of the heel portion 10, and fill the gap in the upper portion of the heel portion 10 on the lateral side of the heel portion 10.

Preferably, a lower edge line 3L of the sponge member 3 extends, while being upwardly slanted, from a medial side of the heel portion 10 to a lateral side thereof via a back side thereof.

In this case, the sponge member 3 will likely fill the gap in the lower portion of the heel portion 10 on the medial side of the heel portion 10, fill the gap behind the calcaneal tuberosity Cp of the heel portion 10 on the back side of the heel portion 10, and fill the gap in the upper portion of the heel portion 10 on the lateral side of the heel portion 10.

Preferably, the sponge member 3 includes:

a first sponge plate 31 extending along a medial side of a heel coming from a back side of the heel and also extending along a lateral side of the heel coming from the back side of the heel; and

a second sponge plate 32 laid on a foot skin side of the first sponge plate 31, the second sponge plate 32 having a smaller area than the first sponge plate 31, wherein:

the second sponge plate 32 is laid on a portion of the first sponge plate 31 while being bonded, glued or welded to the first sponge plate 31;

the thin portion 3 a is formed by a portion of the first sponge plate 31 on which the second sponge plate 32 is not laid; and

the thick portion 3 b is formed by a portion where the second sponge plate 32 is laid on the first sponge plate 31.

In this example, the manufacturing cost will be significantly lower as compared with a case where the sponge member 3 is molded in a mold in a secondary molding process, or the like. Moreover, the sponge member 3 will not have locally dense portions.

Preferably, the second sponge plate 32 is formed by a material having a lower resilience than the first sponge plate 31.

Since the low-resilience second sponge plate 32 placed on the foot skin side maintains, with a small pressure, the shape in conformity with the surface of the foot, it is possible to achieve a desirable foot conformity. On the other hand, when the shape of the heel substantially changes instantaneously, the high-resilience first sponge plate 31 will likely follow such changes. Therefore, the fitting property of the upper will further improve.

In the present invention, “low resilience” means that the speed at which the original shape is restored upon removal of a load of an external force is low. Therefore, when a load of an external force is applied to both of the sponge plates 31 and 32, the high-resilience first sponge plate 31 will deform quickly, and the deformation of the low-resilience second sponge plate 32 will lag behind. Upon removal of the load of the external force off both of the sponge plates 31 and 32, the first sponge plate 31 will quickly restore its original shape, and the restoration of the second sponge plate 32 will lag behind the first sponge plate 31.

Preferably, the second sponge plate 32 is formed by a material having a lower hardness than the first sponge plate 31.

In this case, the low-hardness second sponge plate 32 placed on the foot skin side will softly contact the skin surface of the heel. Therefore, the wearer will unlikely feel compressed.

More preferably, the second sponge plate 32 is formed by a material having a lower resilience and a lower hardness than the first sponge plate 31.

In this case, the fit will further improve, and one will unlikely feel compressed.

In the present invention, the material of the first sponge plate 31 having a high hardness and a high resilience may be, for example, an urethane foam, a silicone foam, or the like, whereas a material having a low hardness and a low resilience may be, for example, an urethane foam, a silicone foam, or the like. Although the material of the high-resilience first sponge plate 31 has a lower resilience than the sponge material used in an ordinary midsole or a sock liner (sock lining), it has a relatively higher resilience than the material of the low-resilience second sponge plate 32.

The hardness of the first sponge plate 31 is preferably 40 to 90 degrees, more preferably 55 to 90 degrees, particularly preferably 70 to 90 degrees, and most preferably 75 to 85 degrees, in terms of the F hardness.

On the other hand, the hardness of the second sponge plate 32 is preferably 10 to 80 degrees, more preferably 10 to 50 degrees, particularly preferably 10 to 30 degrees, and most preferably 15 to 25 degrees, in terms of the F hardness.

The above F hardness is a value obtained through measurement using the Asker rubber hardness meter F-type (from Kobunshi Keiki Co., Ltd.). Note that the hardness of the first sponge plate 31 and the hardness of the second sponge plate 32 will be substantially zero degree if measured by using a JIS C hardness meter.

Preferably, the sponge member 3 further includes a back portion 30 covering a calcaneal tuberosity Cp from directly behind along a virtual line CL dividing the sponge member 3 into the medial side portion 34 and the lateral side portion 35, and the sponge member 3 defines a narrowed portion 36 which is narrowed downwardly along the virtual line CL and which does not cover an area above the calcaneal tuberosity Cp.

In this case, the gap, which likely occurs between the calcaneal tuberosity Cp and an area of the upper behind the calcaneal tuberosity Cp, will be filled by the back portion 30, thereby improving the fitting property. On the other hand, the narrowed portion 36 will accommodate substantial displacement or deformation of the Achilles tendon, and therefore the movement of the Achilles tendon will unlikely be hindered.

In another aspect of the present invention, the upper 1 includes an inner skin 11 placed on a wear's skin side, and an outer skin on an opposite side from the inner skin 11, wherein a sponge member 3 is housed between the inner skin 11 and the outer skin in the heel portion 10;

the sponge member 3 includes a medial side portion 34 covering a medial side of a calcaneal bone Ca, and a lateral side portion 35 covering a lateral side of the calcaneal bone Ca;

the medial side portion 34 covers at least a portion of a lower edge Ce of the calcaneal bone Ca directly below the talus Ta, and the lateral side portion 35 covers an area of the calcaneal bone Ca directly above a point O, wherein the point O bisects a distance between a lower end of a lateral ankle A0 and the lower edge Ce of the calcaneal bone Ca;

the sponge member 3 includes a first sponge plate 31 extending along a medial side of a heel coming from a back side of the heel and also extending along a lateral side of the heel coming from the back side of the heel, and a second sponge plate 32 laid on a foot skin side of the first sponge plate 31, the second sponge plate 32 having a smaller area than the first sponge plate 31; and

the second sponge plate 32 is partially laid on the first sponge plate 31 while being bonded, glued or welded together to the first sponge plate 31.

In this case, the medial side portion 34 of the sponge member 3 fills the narrowed portion directly below the talus Ta. On the other hand, the lateral side portion 35 of the sponge member 3 fills the narrowed portion directly and immediately below the lateral ankle A0. Therefore, narrowed portions on the medial side and the lateral side of the heel will be filled, and the upper 1 will better fit the heel.

The present invention will be understood more clearly from the following description of preferred embodiments taken in conjunction with the accompanying drawings. Note however that the embodiments and the drawings are merely illustrative and should not be taken to define the scope of the present invention. The scope of the present invention shall be defined only by the appended claims. In the accompanying drawings, like reference numerals denote like components throughout the plurality of figures.

Embodiments

Embodiments of the present invention will now be described with reference to the drawings.

FIGS. 4 to 5D Show Embodiment 1

As shown in FIG. 4, the upper 1 includes the inner skin 11 placed on the wear's skin side, and the outer skin 12 placed on the opposite side from the inner skin 11. The sponge member 3 is housed between the inner skin 11 and the outer skin 12 in the heel portion 10.

Note that although the sponge member 3 undergoes substantial compressive deformation, or the like, when manufacturing the shoe, FIG. 4 merely shows the conceptual placement of the sponge member 3. Reference numeral 6 denotes an insole.

The inner skin 11 may be a mesh material, or the like, as well as a woven material or a knit material having desirable stretchability and air-permeability. On the other hand, the outer skin 12 may be a mesh material, or the like, as well as a plate or tape material made of a synthetic leather or a non-foamed synthetic resin having a desirable shape retention.

Note that each of the inner skin 11 and the outer skin 12 may include a single layer or multiple layers. A heel counter or a core well known in the art may be placed.

In the present embodiment, the sponge member 3 includes the first to third sponge plates 31 to 33. The first sponge plate 31 and the second sponge plate 32 are bonded, glued or welded together, and are partially laid on each other. The second sponge plate 32 and the third sponge plate 33 are bonded, glued or welded together, and are partially laid on each other.

The first sponge plate 31 is formed by a sponge having a high resilience and a high hardness. On the other hand, the second and third sponge plates 32 and 33 are formed by a sponge having a low resilience and a low hardness.

Note that the third sponge plate 33 may be of a material having the same physical properties as that of the second sponge plate 32.

As shown in FIGS. 5A to 5D, the first sponge plate 31 extends along the medial side of the heel coming from the back side of the heel and also extends along the lateral side of the heel coming from the back side of the heel. As shown in FIG. 4, the second sponge plate 32 is laid on the foot skin side of the first sponge plate 31, and has a smaller area than the first sponge plate 31 as shown in FIG. 5A. The third sponge plate 33 of FIG. 4 is laid on the foot skin side (the inner skin 11 side) of the second sponge plate 32, and has an even smaller area than the second sponge plate 32 as shown in FIG. 5A.

The sponge member 3 includes the medial side portion 34 covering the medial side of the calcaneal bone Ca as shown in FIG. 5C, and the lateral side portion 35 covering the lateral side of the calcaneal bone Ca as shown in FIG. 5D. The medial side portion 34 and the lateral side portion 35 of FIG. 4 are separated from each other by a medial-lateral center line (virtual line) CL of the heel portion 10 (FIG. 4).

Thus, as shown in FIG. 5B, the sponge member 3 includes the thin portion 3 a having a small thickness, and the thick portion 3 b thicker than the thin portion 3 a. With the sponge member 3 of FIG. 5A unfolded, the perimeter of the thick portion 3 b is surrounded by the thin portion 3 a.

That is, the thin portion 3 a is formed by a portion of the first sponge plate 31 on which no second sponge plate 32 is laid. On the other hand, the thick portion 3 b is formed by a portion where the second sponge plate 32 is laid on the first sponge plate 31.

Note that in the case of three layers as shown in FIG. 5B, the sponge member 3 includes a thickest portion 3 c that is even thicker than the thick portion 3 b. With the sponge member 3 of FIG. 5A unfolded, the perimeter of the thickest portion 3 c is surrounded by the thick portion 3 b.

As shown in FIGS. 5A, 5C and 5D, the lower edge line 3L of the sponge member 3 extends, while being upwardly slanted, from the medial side of the heel portion 10 to the lateral side thereof via the back side thereof. Thus, in the developed view of FIG. 5A where the sponge member 3 is unfolded into a planar shape (plane figure), the level of the centroid of the portion corresponding to the lateral side portion 35, i.e., the lateral first centroid O10, is set to be higher than the level of the centroid of the portion corresponding to the medial side portion 34, i.e., the medial first centroid O11.

As shown in FIGS. 5A, 5C and 5D, the lower edge and upper edge line 3 bL of the thick portion 3 b extends, while being upwardly slanted, from the medial side of the heel portion 10 to the lateral side thereof via the back side thereof. Thus, in the developed view of FIG. 5A, the level of the lateral second centroid O20 of the portion of the thick portion 3 b corresponding to the lateral side portion 35 is set to be higher than the level of the medial second centroid O21 of the portion of the thick portion 3 b corresponding to the medial side portion 34.

The first sponge plate 31 further includes the back portion 30 covering the calcaneal tuberosity Cp (FIG. 5C) from directly behind along the virtual center line CL of FIG. 5A. The first sponge plate 31 has the narrowed portion 36 where the upper edge is narrowed downwardly along the center line CL, which is the medial-lateral center. Because of the narrowed portion 36, the first sponge plate 31 does not cover the area above the calcaneal tuberosity Cp, and the first sponge plate 31 will not therefore compress the Achilles tendon during toe off of FIG. 2( o). On the other hand, protruding portions 37 and 37 protruding upward on opposite sides of the narrowed portion 36 of FIG. 5A will improve the fit on the medial side and the lateral side of the heel.

The first sponge plate 31 of the medial side portion 34 of FIG. 5C covers at least a portion of the lower edge Ce of the calcaneal bone Ca directly below the talus Ta, and covers the majority of the lower half of the calcaneal bone Ca posterior to the medial ankle A1. The second sponge plate 32 of the medial side portion 34 covers an area of the calcaneal bone Ca below the point O1 and does not cover an area above the point O1, wherein the point O1 bisects a distance between the lowermost end point Ae of the medial ankle A1 and the lower edge Ce of the calcaneal bone Ca.

The first and second sponge plates 31 and 32 of the lateral side portion 35 cover both an area of the calcaneal bone Ca directly above the point O and an area of the calcaneal bone Ca directly below the point O, wherein the point O bisects a distance between the lowermost end point Ae of the lateral ankle A0 and the lower edge Ce of the calcaneal bone Ca.

The first sponge plate 31 extends to a point anterior to the lowermost end point Ae of the medial ankle A1 on the medial side of the foot of FIG. 5C, and extends to a point anterior to the lowermost end point Ae of the lateral ankle A0 on the lateral side of the foot of FIG. 5D.

The second sponge plate 32 extends to a point anterior to the posterior end Ab of the medial ankle A1 on the medial side of the foot of FIG. 5C, and extends to a point anterior to the posterior end Ab of the lateral ankle A0 on the lateral side of the foot of FIG. 5D.

The areas of the first sponge plate 31, the second sponge plate 32 and the third sponge plate 33 on the medial side portion 34 are respectively greater than those on the lateral side portion 35. Note that for the lowermost end portion of the foot, a roll-up portion is often formed in the upper 1 itself or in the sock liner (sock lining), in which case there is no need to provide the sponge member 3 on the medial side Med.

In the following examples, like elements to those of Embodiment 1 will be denoted by like reference numerals and will not be further described below, and the following description will mainly focus on what is different from Embodiment 1.

Note that as in Embodiment 2 shown in FIGS. 6A to 6D, the area of the third sponge plate 33 on the lateral side of the foot may be greater than that on the medial side of the foot.

FIGS. 7A to 7D Show Embodiment 3

In the present embodiment, the third sponge plate 33 is absent. In such a case, the thickness of the first and second sponge plates 31 and 32 is preferably made greater than that in Embodiments 1 and 2.

In various embodiments, the thickness of the sponge plates 31 and 32 is preferably about 5 to 15 mm, and more preferably about 7 to 12 mm.

As shown in FIG. 7A, in Embodiment 3, the second sponge plate 32 has a narrowed portion 38 that is narrowed downwardly in the area of the center line CL. The narrowed portion 38, in cooperation with the narrowed portion 36, will further unlikely causes compression on the Achilles tendon.

As shown in FIGS. 7A, 7C and 7D, the second sponge plate 32 has a significantly larger area on the medial side portion 34 than on the lateral side portion 35. The second sponge plate 32 extends to a point anterior to the posterior end Ab of the medial ankle A1 on the medial side portion 34 of FIG. 7C, and the second sponge plate 32 does not extend to the posterior end Ab of the lateral ankle A0 on the lateral side portion 35 of FIG. 7D, with the second sponge plate 32 not covering the anterior half of the calcaneal bone Ca while covering the posterior portion of the calcaneal bone Ca.

FIGS. 8A to 8D Show Embodiment 4

In this example, the medial side portion 34 and the lateral side portion 35 have shapes that are generally in line symmetry with each other about the center line CL.

In the present embodiment, the medial side portion 34 of the first sponge plate 31 covers at least a portion of the lower edge Ce of the calcaneal bone Ca directly below the talus Ta. On the other hand, the lateral side portion 35 of the first sponge plate 31 covers an area of the calcaneal bone Ca directly above the point O, wherein the point O is a bisector between the lower end of the lateral ankle A0 and the lower edge Ce of the calcaneal bone Ca.

The second sponge plate 32 of FIG. 8A includes, at its opposite ends, protruding portions 39 and 39 that coincide with the upper edge line of the first sponge plate 31. The protruding portions 39 will be helpful in positioning the first sponge plate 31 and the second sponge plate 32 with each other.

The sponge member 3 of the present embodiment having a generally line-symmetric shape may lead to a less desirable fitting property as compared with Embodiments 1 to 3. However, the second sponge plate 32 is partially laid on the first sponge plate 31, and the sponge member 3 can be expected to fill the gap between the foot and the upper 1 and improve the fit to some degree. Particularly, the foot conformity will improve by setting the hardness and the resilience of the second sponge plate 32 lower than those of the first sponge plate 31.

On the other hand, Embodiment 4 having a symmetric shape can improve productivity as compared with Embodiments 1 to 3, where it is necessary to provide both a member for the left foot and a member for the right foot, and the left-foot member and the right-foot member cannot be installed incorrectly during the manufacture.

While preferred embodiments have been described above with reference to the drawings, various obvious changes and modifications will readily occur to those skilled in the art upon reading the present specification.

For example, different sponge plates may have the same hardness and the same resilience property.

The sponge member may be divided into two pieces between the medial side and the lateral side, or may be divided into three pieces between the medial side, the back side and the lateral side.

Thus, such changes and modifications are deemed to fall within the scope of the present invention.

The present invention is applicable to a heel portion of an upper.

REFERENCE SIGNS LIST

1: Upper, 10: Heel portion, 11: Inner skin, 12: Outer skin

2: Sole

3: Sponge member, 30: Back portion, 31: First sponge plate, 32: Second sponge plate, 33: Third sponge plate, 34: Medial side portion, 35: Lateral side portion, 36: Narrowed portion, 37: Protruding portion, 38: Narrowed portion, 39: Protruding portion

3 a: Thin portion, 3 b: Thick portion, 3 c: Thickest portion, 3 bL: Lower edge line of thick portion

3L: Lower edge line of sponge member

6: Insole

A0: Lateral ankle, A1: Medial ankle, Ae: Lowermost end point, Ab: Posterior end

Ca: Calcaneal bone, Ce: Lower edge of calcaneal bone, Cp: Calcaneal tuberosity

CL: Center line

Fa: Area directly below lateral ankle, Fb: Area at same height as on lateral side of foot, Fu: Lower portion

M: Marker, M1: Marker attached to medial ankle, M2: Marker attached to lateral ankle

O, O1: Bisector point

O10: Lateral first centroid, O11: Medial first centroid, O20: Lateral second centroid

O21: Medial second centroid

Sp: Sponge plate

Ta: Talus 

1. A structure of an upper for improving a fitting property of a heel portion 10 of the upper 1 of a shoe, wherein: the upper 1 includes an inner skin 11 placed on a wear's skin side, and an outer skin placed on an opposite side from the inner skin 11, wherein a sponge member 3 is housed between the inner skin 11 and the outer skin in the heel portion 10; the sponge member 3 includes a medial side portion 34 covering a medial side of a calcaneal bone Ca, and a lateral side portion 35 covering a lateral side of the calcaneal bone Ca; and in a developed view where the sponge member 3 is unfolded into a planar shape, a level of a lateral first centroid O10 of a portion corresponding to the lateral side portion 35 is set to be higher than a level of a medial first centroid O11 of a portion corresponding to the medial side portion
 34. 2. The structure according to claim 1, wherein the medial side portion 34 covers at least a portion of a lower edge Ce of the calcaneal bone Ca directly below a talus Ta, and the lateral side portion covers an area of the calcaneal bone Ca directly above a point O, wherein the point O bisects a distance between a lowermost end point Ae of a lateral ankle A0 and the lower edge Ce of the calcaneal bone Ca.
 3. The structure according to claim 2, wherein the sponge member 3 includes a thin portion 3 a having a small thickness, and a thick portion 3 b thicker than the thin portion 3 a, and wherein with the sponge member 3 unfolded, a perimeter of the thick portion 3 b is surrounded by the thin portion 3 a.
 4. The structure according to claim 3, wherein in a developed view where the thick portion 3 b is unfolded into a planar shape, a level of a lateral second centroid O20 of a portion of the thick portion 3 b corresponding to the lateral side portion is set to be higher than a level of a medial second centroid O21 of a portion of the thick portion 3 b corresponding to the medial side portion
 34. 5. The structure according to claim 3, wherein a lower edge line 3 bL of the thick portion 3 b extends, while being upwardly slanted, from a medial side of the heel portion 10 to a lateral side of the heel portion 10 via a back side of the heel portion
 10. 6. The structure according to claim 2, wherein a lower edge line 3L of the sponge member 3 extends, while being upwardly slanted, from a medial side of the heel portion 10 to a lateral side of the heel portion 10 via a back side of the heel portion
 10. 7. The structure according to claim 3, wherein the sponge member 3 comprises: a first sponge plate 31 extending along a medial side of a heel coming from a back side of the heel and also extending along a lateral side of the heel coming from the back side of the heel; and a second sponge plate 32 laid on a foot skin side of the first sponge plate 31, the second sponge plate 32 having a smaller area than the first sponge plate 31, wherein: the second sponge plate 32 is laid on a portion of the first sponge plate 31 while being bonded, glued or welded to the first sponge plate 31; the thin portion 3 a is formed by a portion of the first sponge plate 31 on which the second sponge plate 32 is unlaid; and the thick portion 3 b is formed by a portion where the second sponge plate 32 is laid on the first sponge plate
 31. 8. The structure according to claim 7, wherein the second sponge plate 32 is formed by a material having a lower resilience than the first sponge plate
 31. 9. The structure according to claim 7, wherein the second sponge plate 32 is formed by a material having a lower hardness than the first sponge plate
 31. 10. The structure according to claim 7, wherein the second sponge plate 32 is formed by a material having a lower resilience and a lower hardness than the first sponge plate
 31. 11. The structure according to claim 2, wherein the sponge member 3 further comprises a back portion 30 covering a calcaneal tuberosity Cp from directly behind along a virtual line CL dividing the sponge member 3 into the medial side portion 34 and the lateral side portion 35, and the sponge member 3 defines a narrowed portion 36 that is narrowed downwardly along the virtual line CL without covering an area above the calcaneal tuberosity Cp.
 12. A structure for improving a fitting property of a heel portion 10 of an upper 1 of a shoe, wherein: the upper 1 includes an inner skin 11 placed on a wear's skin side, and an outer skin on an opposite side from the inner skin 11, wherein a sponge member 3 is housed between the inner skin 11 and the outer skin in the heel portion 10; the sponge member 3 includes a medial side portion 34 covering a medial side of a calcaneal bone Ca, and a lateral side portion 35 covering a lateral side of the calcaneal bone Ca; the medial side portion 34 covers at least a portion of a lower edge Ce of the calcaneal bone Ca directly below a talus Ta, and the lateral side portion 35 covers an area of the calcaneal bone Ca directly above a point O, wherein the point O bisects a distance between a lower end of a lateral ankle A0 and the lower edge Ce of the calcaneal bone Ca; the sponge member 3 includes a first sponge plate 31 extending along a medial side of a heel coming from a back side of the heel and also extending along a lateral side of the heel coming from the back side of the heel, and a second sponge plate 32 laid on a foot skin side of the first sponge plate 31, the second sponge plate 32 having a smaller area than the first sponge plate 31; and the second sponge plate 32 is partially laid on the first sponge plate 31 while being bonded, glued or welded together to the first sponge plate
 31. 13. The structure according to claim 12, wherein the sponge member 3 further comprises a back portion 30 covering a calcaneal tuberosity Cp from directly behind along a virtual line CL dividing the sponge member 3 into the medial side portion 34 and the lateral side portion 35, and the sponge member 3 defines a narrowed portion 36 that is narrowed downwardly along the virtual line CL without covering an area above the calcaneal tuberosity Cp.
 14. The structure according to claim 12, wherein the second sponge plate 32 is formed by a material having a lower resilience and/or a lower hardness than the first sponge plate
 31. 